Method of making macroporous anion exchange resins
View Patent ↗Methods of making macroporous anion exchange resins are described. The macroporous anion exchange resins are in the form of particles such as beads that contain a hydrophilic, crosslinked, (meth)acrylic-type polymeric material. Additionally, methods of purifying a negatively charged material using the macroporous anion exchange resins, methods of making chromatographic columns that contain the macroporous anion exchange resins, methods of making filter elements that contain the macroporous anion exchange resins, and methods of making porous composite materials that contain the macroporous anion exchange resins are described.
1. A method of preparing a macroporous anion exchange resin, the method comprising:
forming an aqueous phase composition comprising
a) a monomer mixture comprising
i) a crosslinking monomer comprising N,N′-alkylenebis(meth)acrylamide, N,N′-heteroalkylenebis(meth)acrylamide, or a combination thereof in an amount in a range of 15 to 90 weight percent based on a weight of monomers in the monomer mixture; and
ii) a positively charged ionic monomer,
wherein substantially all the monomers in the monomer mixture have a lipophilicity index less than or equal to 20; and
b) a water-soluble porogen of Formula I
R 1 —(R 2 —O) n —R 3 (I)
wherein
R 1 is hydroxy, alkoxy, carboxy, acyloxy, or halo;
each R 2 is independently an alkylene having 1 to 4 carbon atoms;
R 3 is hydrogen, alkyl, carboxyalkyl, acyl, or haloalkyl;
n is an integer of 1 to 1,000; and
c) an aqueous phase solvent mixture comprising water and a mono-alcohol having 1 to 4 carbon atoms, wherein the mono-alcohol is present in an amount of at least 20 weight percent based on a total weight of the aqueous phase solvent mixture;
suspending the aqueous phase composition in a non-polar organic solvent;
polymerizing the monomer mixture to form particles of polymeric material; and
removing the porogen from the particles to form a macroporous anion exchange resin.
2. The method of claim 1 , wherein the macroporous anion exchange resin has pores having a diameter less than or equal to 200 nanometers.
3. The method of claim 2 , wherein the macroporous anion exchange resin has a pore volume of at least 0.10 cubic centimeters per gram and a surface area of at least 20 m 2 /g.
4. The method of claim 1 , wherein the crosslinking monomer is present in an amount of 25 to 75 weight percent based on a total weight of monomers in the monomer mixture and the positively charged ionic monomer is present in an amount of 25 to 75 weight percent based on the total weight of the monomers in the monomer mixture.
5. The method of claim 1 , wherein the positively charged ionic monomer is of Formula II or a quaternary ammonium salt thereof
wherein
R 1 is hydrogen or methyl;
L is oxy or —NH—;
Y is an alkylene; and
each R 5 is independently hydrogen, alkyl, hydroxy alkyl, amino alkyl, or the two R 5 groups taken together with the nitrogen atom to which they are attached form a heterocyclic group that is aromatic, partially unsaturated, or saturated, wherein the heterocyclic group can optionally be fused to a second ring that is aromatic, partially unsaturated, or saturated.
6. The method of claim 1 wherein R 2 is ethylene or propylene.
7. The method of claim 1 , wherein R 1 is hydroxy and R 3 is hydrogen or R 1 is hydroxy and R 3 is alkyl.
8. The method of claim 1 , wherein the porogen comprises a polyethylene oxide with a molecular weight no greater than 1,000 g/mole.
9. The method of claim 8 , wherein the polyethylene oxide has hydroxy end groups.
10. The method of claim 1 , wherein the porogen comprises a mixture of a first porogen comprising an alkylene glycol and a second porogen comprising a polyalkylene oxide.
11. The method of claim 10 , wherein the first porogen comprises ethylene glycol and the second porogen comprises polyethylene oxide with hydroxy end groups.
12. The method of claim 1 , wherein the mono-alcohol is present in an amount of at least 50 percent based on the total weight of the aqueous phase solvent mixture.